Biofuel is a broad term covering any biomass related product being used for fuel applications. The origin of the biomass can be from plant, or animal source. The biodiesel is a form of biofuel and it is blended with diesel. In general, the term biodiesel is in concurrent with biofuel and anywhere biodiesel implies the blend of biomass with diesel, petrol or any petroleum product. It is thus distinguished from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some modified diesel vehicles.
Biodiesel reduces emissions of carbon monoxide (CO) by approximately 50% and by 78% on a net lifecycle basis because the carbon in biodiesel emissions is recycled from carbon that was in the atmosphere, rather than the carbon introduced from petroleum that was sequestered in the earth's crust.                Biodiesel contains fewer aromatic hydrocarbons: benzofluoranthene: 56% reduction; Benzopyrenes: 71% reduction.        Biodiesel can reduce by as much as 20% the direct (tailpipe) emission of particulates, small particles of solid combustion products, on vehicles with particulate filters, compared with low-sulfur (<50 ppm) diesel. Particulate emissions are reduced by around 50%, compared with fossil-sourced diesel.        Biodiesel has a higher cetane rating than petrodiesel, which can improve performance and clean up emissions compared to crude petrodiesel (with cetane lower than 40).        Biodiesel is biodegradable and non-toxic—the U.S. Department of Energy confirms that biodiesel is less toxic than table salt and biodegrades as quickly as sugar.        The flash point of biodiesel (>150° C.) is significantly higher than that of petroleum diesel (64° C.) or gasoline (−45° C.). The gel point of biodiesel varies depending on the proportion of different types of esters contained. However, most biodiesel, including that made from soybean oil, has a somewhat higher gel and cloud point than petroleum diesel. In practice, this often requires heating of storage tanks, especially in cooler climates.        Pure biodiesel (B 100) can be used in any petroleum diesel engine, though it is more commonly used in lower concentrations. Some areas have mandated ultra-low sulfur petrodiesel, which reduces the natural viscosity and lubricity of the fuel due to the removal of sulfur and certain other materials. Additives are required to make ULSD properly flow in engines, making biodiesel one popular alternative. Ranges as low as 2% (B2) have been shown to restore lubricity. Many municipalities have started using 5% biodiesel (B5) in snow-removal equipment and other systems. Same way, diesel containing 20% of biomaterial can be named B20, 10% will be B10 etc. This notation is convenient to identify the approximate percentage of biomaterial in fuels.Drawbacks of Biodiesel        
Limited availability: There is ongoing research into finding more suitable crops and improving oil yield. Using the current yields, vast amounts of land and fresh water would be needed to produce enough oil to completely replace fossil fuel usage. It would require twice the land area of the US to be devoted to soybean production, or two-thirds to be devoted to rapeseed production, to meet current US heating and transportation needs. Global biodiesel production reached 3.8 million tons in 2005. On the other hand, the estimated transportation fuel and home heating oil used in the United States is about 230 billion US gallons. There is a need for a biomaterial which is abundant in nature, which is preferably non-edible or a product of a plant wherein some part of it is edible (like fruit, leaves) and some of it is non-edible (stem, seeds). The major drawback or using corn or soybean kinds of plant products is that they are food materials and with severe shortage of food in the world, it is not justified to use these materials for biofuel production. Ideally there is a need for biofuel source where the biomaterial usage actually creates more food material for the world rather than consuming it.
Gelling: The temperature at which pure (B100) biodiesel starts to gel varies significantly and depends upon the mixture of esters and therefore the feedstock oil used to produce the biodiesel. For example, biodiesel produced from low erucic acid varieties of canola seed (RME) starts to gel at approximately −10° C. Biodiesel produced from tallow tends to gel at around +16° C. As of 2006, there are a very limited number of products that will significantly lower the gel point of straight biodiesel. We need a biofuel which does not contain any esters when mixed with diesel for biodiesel formulation to prevent gelling at low temperatures. Ideally, we need a plant material which gels at below −10° C. and when mixed with petroleum products, the overall biofuel's gelling temperature drops below −15° C.
Contamination with water: Biodiesel may contain small but problematic quantities of water. Although it is hydrophobic (non-miscible with water molecules), it is said to be, at the same time, hygroscopic to the point of attracting water molecules from atmospheric moisture; in addition, there may be water that is residual to processing or resulting from storage tank condensation. The presence of water is a problem because it reduces the heat of combustion of the bulk fuel. This means more smoke, harder starting, less power. Water causes corrosion of vital fuel system components: fuel pumps, injector pumps, fuel lines, etc. It freezes to form ice crystals near 0° C. (32° F.). These crystals provide sites for nucleation and accelerate the gelling of the residual fuel. Water accelerates the growth of microbe colonies, which can plug up a fuel system. Biodiesel users who have heated fuel tanks therefore face a year-round microbe problem. We need a biofuel that contains less water to prevent above stated problems, preferably which does not involve transesterification procedure involving alcohols, which are the main source of water content in biofuels. We need a bio product which is preferably distilled at high temperatures under vacuum, has comparable carbon content of diesel and does not involve any chemical processing like transesterification.
Transesterification of used oil to convert to biodiesel: separation from glycerol: The process of converting vegetable oil into biodiesel fuel is called transesterification. Chemically, transesterification means taking a triglyceride molecule or a complex fatty acid, neutralizing the free fatty acids, removing the glycerin, and creating an alcohol ester. This is accomplished by mixing methanol with sodium hydroxide to make sodium methoxide. This dangerous liquid is then mixed into vegetable oil. The entire mixture then settles. Glycerin is left on the bottom and methyl esters, or biodiesel, are left on top and the methyl esters are washed and filtered. The resulting biodiesel fuel when used directly in a Diesel engine will burn up to 75% cleaner than petroleum D2 fuel. The problem with glycerol presence is it is very hydrophilic and can form hydrogen bond with water and invariably increases the moisture content in biofuel. So we need a biofuel which does not contain any glycerol or its derivatives in its composition. It is strongly preferred to a biosource without involving any transesterification.
Decrease in Mileage: When the biofuels are used in diesel engines, they tend to decrease the mileage or fuel efficiency of that engine by 10-30%. This is serious disadvantage because, whatever cost effectiveness, less pollution we are obtaining by switching to biofuels is not worth the effort due to less mileage, which eventually balance for the pollution and cost of petroleum products. We need a biosource which has comparable or higher calorific value compared to petroleum products, which gives a comparable or improved mileage when compared to diesel.
Wear and tear on engine: When biofuels are used, it is often that engine wear and tear is increased and the engine tends to make more noise and needs frequent repairs. We need a biosource which does not cause frequent engine problems and which decreases engine noise and helps in smooth running of the engine.
Hence, there is a need for finding alternative biodiesel sources which retain the benefits of biodiesel and eliminate or, at least, reduce the potential drawbacks discussed above.
An ideal biofuel should have following characteristics, 1) It needs to be from a renewable source, which improves food production rather depleting it; 2) Which does not contain any ester products and does not form gel or clouding at above −10° C.; 3) Does not involve any process like transesterification which brings more water into the biofuel; 4) does not contain glycerol; 5) does not cause significant decrease in fuel efficiency when compared to petroleum products and preferably produces comparable or improved fuel efficiency; and 6) decreases wear and tear on engine and produces less noise.
In this invention, we describe distilled technical cashew nut shell liquid (DT-CNSL) as an alternative biosource that has distinct advantages over other vegetable oils, which can be converted into biodiesel without involving the transesterification process.
CNSL Industrial Applications
CNSL derivatives, resins and polymers have a number of applications. CNSL-aldehyde condensation products and CNSL-based phenolic resins are used in applications such as surface coatings, adhesives, varnishes and paints. Various polyamines synthesized from CNSL or cardanol are used as curing agents for epoxy resins.
CNSL and its derivatives have been used as antioxidants, plasticisers and processing aids for rubber compounds and modifiers for plastic materials. Resins based on the reaction products of cardanol, phenol and formaldehyde are used to improve the resistance of rubber articles to cracking and ozone. CNSL, cardanol and cardol are all used to provide oxidative resistance to sulfur-cured natural rubber products.
A number of products based on CNSL are used as antioxidants, stabilizers and demulsifiers for petroleum products. Metal xanthates of partially hydrogenated, sulfurized cardanol is used to lower the pour point of lubricating oils as well as acting as antioxidant and anticorrosive properties. Soluble metal derivatives of CNSL are used to improve the resistance to oxidation and sludge formation of lubricating oils. Oxidized CNSL and its derivatives are used as demulsifying agents for water in oil type petroleum emulsions.